1. Field of the Invention
This invention relates to a sintering method, a fusion welding method, electronic components and sensors, and more particularly to a sintering method and fusion welding method capable of film formation and fusion welding without raising a substrate temperature, and to electronic components and sensors used in each of these methods.
2. Description of the Prior Art
Various metallic and non-metallic films are formed during a fabrication process of electronic components. These films are formed mainly by vacuum deposition, spattering, CVD, and the like, and plating and screen printing are also employed depending on fabrication conditions.
In the fabrication process of electronic components, there often occur the cases where the temperature of a substrate on which a film is to be formed cannot be raised but the film which is from several microns to a dozen of microns thick must be worked or etched in a predetermined shape. In such cases, vacuum deposition and spattering are not employed because a long period of time is necessary for forming the film, and an extended period of time is also required for etching unnecessary portions if the film thickness increases and accuracy drops. Particularly, vacuum deposition is not employed because the substrate is heated by radiation from a vacuum deposition source. Screen printing is not employed, either, because the substrate must be heated as a whole in order to bake a printed paste.
Therefore, plating is employed under the conditions such as described above. Though plating can form a film without heating the substrate, it is not free from the problems in that the substrate must be dipped into a plating solution, a long period of time is necessary for plating, process steps such as an electrode formation step, a photoresist step, and the like become complicated as a whole, the film thickness is likely to be non-uniform and the yield is low. Although these problems result in the increase in the cost of production, plating is employed at present under the above-mentioned condition.
High cost of production is unavoidable in the case of plating because its process steps are complicated and its yield is low. Particularly because plating is a wet process, it renders various disadvantages to other process steps.
The technique disclosed in Japanese Patent Laid-Open No. 160975/1982 can be cited as a prior art reference related to the sintering technique which is proposed hereby by the present invention.
Sintering of ultra-fine particles by laser is known from this prior art reference (Japanese Patent Laid-Open No. 160975/1982) but this reference does not deal with ultra-fine metal powder as the object of laser radiation and cannot be applied to the fabrication of electronic components, for example.
On the other hand, mention can be made of U.S. Pat. No. 4,612,208 as a reference relating to laser radiation technique which is proposed by the present invention.
In accordance with this prior art technique, however, a lamp-black itself has no longer the trace of the original form by laser radiation, and the product or treated object is different from that of the present invention.